Aristotle - The Organon - index for ANALYTICA PRIORIA Book 1 Part 4

The first figure

Whenever three terms are so related to one another that the last
is contained in the middle as in a whole, and the middle is either
contained in, or excluded from, the first as in or from a whole, the
extremes must be related by a perfect syllogism.

If then the terms are universally related, it is clear in this
figure when a syllogism will be possible and when not, and that if a
syllogism is possible the terms must be related as described, and if
they are so related there will be a syllogism.

But if one term is related universally, the other in part only, to
its subject, there must be a perfect syllogism whenever universality
is posited with reference to the major term either affirmatively or
negatively, and particularity with reference to the minor term
affirmatively:

But if the universality is posited with respect to the minor term
either affirmatively or negatively, a syllogism will not be
possible, whether the major premiss is positive or negative,
indefinite or particular:

Nor when the major premiss is universal, whether affirmative or
negative, and the minor premiss is negative and particular, can
there be a syllogism, whether the minor premiss be indefinite or
particular:

Further since it is indefinite to say some C is not B, and it is
true that some C is not B, whether no C is B, or not all C is B, and
since if terms are assumed such that no C is B, no syllogism follows
(this has already been stated) it is clear that this arrangement of
terms will not afford a syllogism:

Nor can there in any way be a syllogism if both the relations of
subject and predicate are particular, either positively or
negatively,
or the one negative and the other affirmative, or one indefinite and
the other definite, or both indefinite.